1. Field of the Invention
The present invention provides methods and a related apparatus for decreasing delay time and power consumption of a wireless mouse, and more particularly, methods for decreasing delay time and power consumption by changing a report rate of the wireless mouse.
2. Description of the Prior Art
From traditional functions, such as document processing and program operating, to modern multimedia, game playing, etc., a personal computer has become an important role in our daily life. Mouses and keyboards used for controlling the PC have improved too. As graphical user interfaces become the main stream interface, precision of a mouse becomes more and more important. In addition, with wireless communication technology, a traditional mouse, which transmits signals to a computer system with physical wires, can be replaced by a wireless mouse. However, owing to limitations of wireless communication, a report rate of the prior art wireless mouse cannot match the same level as the wired mouse. The word “report” of the report rate means that the wireless mouse transmits detected displacement and switch statuses to the computer system, while report per second, or RPS, is a term used to count the report rate, meaning how many signal counts are transmitted to the computer each second. The larger the RPS is, the more moving consistency there will be between a cursor in the monitor and the mouse in a user's hand. In general, the report rate of a wired USB mouse is between 100 Hz and 125 Hz, or between 100 and 125 report counts per second, while the report rate of the wireless mouse is between 60 Hz and 80 Hz. Therefore, the user can feel an obvious difference between the wired mouse and the wireless mouse, especially for fast moving operations, such as PC games, drafting, and web surfing.
Please refer to FIG. 1, which illustrates a block diagram of a prior art wireless mouse 100. The wireless mouse 100 includes a data receiver 102, a logic module 104, a radio-frequency transmitter 106, and a radio-frequency receiver 108. The data receiver 102 receives data pertaining to displacement and the switch status of the wireless mouse 100 and transmits the data to the logic module 104. The logic module 104 transforms data received by the data receiver 102 to packets and transmits the packets to the radio-frequency transmitter 106. The radio-frequency transmitter 106 transmits the packets through the radio-frequency receiver 108 to a computer system sequentially, so as to show effects of the displacement data and the switch status data on a monitor of the computer system.
Please refer to FIG. 2, which illustrates a schematic diagram of a packet 200 outputted from a radio-frequency transmitter of a prior art wireless mouse. The packet 200 includes blocks 202, 204, 206, 208, 210, 212, and 214 with bit lengths of 1, 8, 8, 8, 8, 8, and 1 bit. So, the total bit length of the packet 200 is 42 bits. The blocks 202 and 214 indicate a start and a stop of the packet 200. The blocks 204, 206, 208, and 210 store an x-axis displacement data, a y-axis displacement data, a scroll-wheel displacement data, and a switch status data of the wireless mouse. In addition, the block 212 is an 8-bit cyclic redundancy check, or CRC, block.
In general, the prior art wireless mouse transmits signals with a technique of binary frequency shift keying, or BFSK, meaning that bits (or symbols) 1 and 0 are transmitted with two sinusoidal waves having different frequencies. Take a prior art wireless mouse with an intermediate frequency at 27 MHz for example, in which a bit 0 is represented by a 27.1 MHz sinusoidal wave, and a bit 1 is represented by a 26.9 MHz sinusoidal wave. In addition, a split-phase coding, such as a Manchester coding, has zero power at a direct-current level, and includes a zero crossing within a bit interval, which can increase correctness. Therefore, the prior art wireless mouse usually applies the Manchester coding. Please refer to FIG. 3, which illustrates a schematic waveform diagram of a prior art Manchester code. As shown in FIG. 3, transmitting one bit needs 2T duration. Therefore, if 1T duration of transmitting time is 160 μs, transmitting a packet of the bit needs 13.44 ms (42 bit×2×160 μs=13.44 ms) with the prior art wireless mouse. In the same case, the wired mouse uses 8 ms, which is the main reason that the report rate of the wireless mouse is less than that of the wired mouse.
Moreover, unlike the wired mouse powered by the computer system through the physical wires, the transmitter of the wireless mouse must include an independent power supply device. Since the report rate of the prior art mouse is fixed, the mouse consumes the same amount of power in transmitting packets no matter how fast the mouse moves. Such power management is inefficient. For example, please refer to FIG. 4, which illustrates a schematic diagram of a prior art mouse when transmitting four packets. Each packet needs 8 ms, so the total time of using power for transmitting the four packets is 32 ms.
In short, the wireless mouse is convenient, but is limited by the low report rate and the inefficient power management.